1. Technical Field of the Invention
The present invention relates to an apparatus for controlling swivel angles of headlights mounted on a vehicle (a headlight swivel controller), which controls a swivel angle of headlights which are mounted on the front of a vehicle in a horizontal plane to the vehicle body.
2. Description of the Related Art
A headlight swivel controller for controlling a swivel angle of headlights to an angle corresponding to a curvature of a road in front of a vehicle by controlling a driving device for headlights is known. Even when the vehicle is running on a curved road or even in a case where a curved road is present in front of the vehicle, the headlight swivel controller enables making an area illuminated by the headlights closer to the visible direction of the driver by changing the swivel angle of the headlights according to the shape of the road in front of the vehicle.
As a headlight swivel controller as described above, a device for determining a shape of a road in front of a vehicle based on a steering angle is known. Furthermore, as disclosed in Japanese Patent Application (unexamined) No. 2003-48481, a device for acquiring information on a shape of a road in front of a vehicle from a navigation apparatus is also known.
Generally speaking, since the former method is capable of judging a road shape more accurately, a steering angle swivel control based on a steering angle is executed when it can be judged that steering operation has been performed. Meanwhile, a navigation collaborative control using road information from the navigation apparatus is executed in a case where although a curved road is present in front of the vehicle but steering operation has been performed since the vehicle is still running on a straight road.
Meanwhile, there are some cases where a bypass road which is different from an original road is formed because of road construction or the like in actual roads. As a matter of course, the bypass road is not contained in road map data. Accordingly, in a case where the road map data is acquired from the navigation apparatus and the swivel angle is controlled based on the acquired road map data, a wrong control may be executed at a place where a temporary bypass road is formed.
In addition, in many cases a temporary bypass road has a shape in which the change curvature direction continuously changes within a short district. In a case where the curvature direction changes within a short district, the line of sight of the driver may be oriented not to a curved road or straight road on which the vehicle is currently running, but to a curved road or straight road which is coming next, or to another curved road or straight road after that. In this case, if the swivel angle is controlled based on the steering angle which corresponds to the current curved road, the swivel angle may be controlled into a wrong direction. In other words, a wrong control may be executed at a place where a temporary bypass road is formed, also when the steering angle swivel control is executed.